The present invention relates generally to reducing pollutant emissions from combustion processes, and more particularly, to a gaseous reductant injection control system for exhaust aftertreatment of nitrogen oxide (NOx) or ammonia (NH3) emissions generated from a lean-burn engine.
Lean-burn engines, such as those used by diesel-powered and natural gas-powered vehicles, equipment, and generators combust at high air-to-fuel ratios in comparison with rich-burn engines. By nature, lean-burn engines use less fuel while producing equivalent power of similar-sized rich-burn engines. However, lean-burn engines have increased NOx and NH3 emissions generally due to slow burn rates associated with the lean mixtures of fuel (i.e., excess air introduced with the fuel). Aftertreatment options are typically used to reduce NOx and NH3 emissions from the exhaust of the lean-burn engines.